Structural and spectroscopic study of 5,7-dihydroxy-flavone and its complex with aluminum

Castro, G.T.; Blanco, Susana

doi:10.1016/j.saa.2003.11.022

Cited by 36 publications

(23 citation statements)

References 23 publications

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“…The UV spectrum showed absorption maxima at 271 and 330 nm, characteristic of flavone derivatives (Mabry et al, 1970), addition of aluminium chloride produced a large bathochromic shift of band I (60 nm) characteristic of 5,7 dihydroxy flavone which did not show any change on addition of dil. HCl ( Castro and Blanco, 2004). The IR spectrum exhibited a broad band hydroxyl absorption band at 3418 cm À1 , a carbonyl band at 1618 cm À1 and methoxyl band at 2928 cm À1 .…”

Section: Resultsmentioning

confidence: 99%

Biflavonoids from Lonicera japonica

et al. 2005

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Section: Resultsmentioning

confidence: 99%

Biflavonoids from Lonicera japonica

et al. 2005

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“…The stability constants for the 1:1 and 1:2 complexes formed under the different solvent conditions

were determined using the relationship (3) according to the method of reference [ 30 ] for the 1:1 complex formation corresponding to the equilibrium of Equation (1),

and using the relationship (4) for the 1:2 complex formation corresponding to the equilibrium of Equation (2),

…”

Section: Resultsmentioning

confidence: 99%

Genistein Binding to Copper(II)—Solvent Dependence and Effects on Radical Scavenging

Yang

Liu

et al. 2017

Molecules

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Genistein, but not daidzein, binds to copper(II) with a 1:2 stoichiometry in ethanol and with a 1:1 stoichiometry in methanol, indicating chelation by the 5-phenol and the 4-keto group of the isoflavonoid as demonstrated by the Jobs method and UV-visible absorption spectroscopy. In ethanol, the stability constants had the value 1.12 × 1011 L2∙mol−2 for the 1:2 complex and in methanol 6.0 × 105 L∙mol−1 for the 1:1 complex at 25 °C. Binding was not detected in water, as confirmed by an upper limit for the 1:1 stability constant of K = 5 mol−1 L as calculated from the difference in solvation free energy of copper(II) between methanol and the more polar water. Solvent molecules compete with genistein as demonstrated in methanol where binding stoichiometry changes from 1:2 to 1:1 compared to ethanol and methanol/chloroform (7/3, v/v). Genistein binding to copper(II) increases the scavenging rate of the stable, neutral 2,2-diphenyl-1-picrylhydrazyl radical by more than a factor of four, while only small effects were seen for the short-lived but more oxidizing β-carotene radical cation using laser flash photolysis. The increased efficiency of coordinated genistein is concluded to depend on kinetic rather than on thermodynamic factors, as confirmed by the small change in reduction potential of −0.016 V detected by cyclic voltammetry upon binding of genistein to copper(II) in methanol/chloroform solutions.

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“…Flavonoids have strong coordination ability toward a wide range of cations such as iron(II) 16, chromium(III) 17, aluminum(III) 14, 18–21, and lanthanide 13, 22, 23 ions, which is ascribed to the presence of multiple hydroxyl groups and the carbonyl group on the heterocyclic ring of their chemical structure. Experimental studies reveal that the preferred complexation sites for the flavonoids involve the hydroxyl group on carbon 3 or 5 and the adjacent 4‐carbonyl group 18–21. Aluminum(III) and lanthanide ions such as terbium(III) form fluorescent chelates with these compounds, which have different fluorescent features.…”

Section: Resultsmentioning

confidence: 99%

Luminescent determination of flavonoids in orange juices by LC with post‐column derivatization with aluminum and terbium

Andreu-Navarro

Fernández-Romero

Gómez‐Hens

2010

J of Separation Science

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A new post-column derivatization system is described and applied to the determination of flavonoids in citric beverages after their separation by LC using a monolithic column. The derivatization involves the formation of the chelates of the analytes with aluminum (III) and terbium (III) in the presence of the surfactant SDS and the measurement of the terbium sensitized luminescence at lambda(ex) 360 and lambda(em) 545 nm. Naringin, hesperidin, quercetin, naringenin, and kaempferol have been chosen as analyte models. The large Stokes shift and the relatively long wavelength emission of terbium(III) can minimize interferences from background sample matrix, which usually emit at shorter wavelengths. Calibration graphs were constructed in the intervals 6.0-1700 ng/mL naringin, 9.8-1700 ng/mL hesperidin, 2.1-2000 ng/mL quercetin, 5.2-1500 ng/mL naringenin and 2.5-2000 ng/mL kaempferol, with regression coefficients higher than 0.9935 in all instances. The precision of the method, expressed as RSD%, was established at two concentration levels, with values of 1.3 and 4.7%, which corresponded to the minimal and maximal error zones of the calibration graphs. The practical usefulness of the method is demonstrated by the analysis of orange juices, which were diluted and directly injected into the chromatographic system, obtaining recoveries between 86.9 and 108.2%.

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Structural and spectroscopic study of 5,7-dihydroxy-flavone and its complex with aluminum

Cited by 36 publications

References 23 publications

Biflavonoids from Lonicera japonica

Biflavonoids from Lonicera japonica

Genistein Binding to Copper(II)—Solvent Dependence and Effects on Radical Scavenging

Luminescent determination of flavonoids in orange juices by LC with post‐column derivatization with aluminum and terbium

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